The invention relates to a carbon monoxide monitor for use on marine vehicles and more particularly to an apparatus and method for monitoring the health hazard to the occupants of a marine vehicle occasioned by breathing the carbon monoxide fumes generated by the internal combustion engines of the marine vehicle.
Carbon monoxide is an odorless, colorless, and tasteless gas that is lethal if present in sufficient concentration and if at a particular concentration it is breathed over a sufficient period of time.
Carbon monoxide detectors are available for use on marine vehicles, however, these instruments function only to detect a specific selected level of carbon monoxide and to sound an alarm and/or to provide a visual indication when this level has been exceeded. It is perfectly safe to breathe a relatively low concentration of carbon monoxide e.g., 50 PPM, over an extended period of time, whereas it would be lethal to breathe a high concentration of carbon monoxide e.g., 450 PPM, over even a relatively short period of time. Thus, prior art detectors that are set at the lower level will give an alarm even though no health hazard exists. On the other hand, prior art detectors that are set to the higher level will not alarm even though carbon monoxide concentration below the alarm set point is present that may be lethal if breathed over a sufficient period of time, as for example, the amount of carbon monoxide that may be breathed by a person sleeping on a marine vehicle while internal combustion engines of the vehicle, or other sources of carbon monoxide, are operating.
It has also been determined that the lethality of carbon monoxide is not only a function of concentration and the length of time a person breathes carbon monoxide at that concentration, but also a function of such factors as the rate of diffusion of carbon monoxide into the lungs, barometric pressure, minute respiratory volume and level of exertion or work which together establish a level of carbon monoxhemoglobin (COHb), in the blood. It is the level of COHb in the blood that constitutes a health hazard rather than carbon monoxide concentration or the length of time that carbon monoxide at that concentration is breathed per se.